Quick question about recompiling with GD library

Hello, I have png/jpeg support and gd 1.8.3 I see, however, some linux ./configure examples that just use --with-gd and no --with=/usr/local/png or whatever the question is, would --with-gd be enough to create/add text to jpeg/png or *only* if they are included? Just want to double check Thanks Joel Ps. Is there a way php can access the .so file without compiling that library? I saw an example where they connected to the ming (To create flash files) .so file, is that a workaround from having to ./configure and is it bad practice?